End cap relief valve mechanism for a filter

ABSTRACT

An oil filter comprises a housing that is open at one end and has an end plate connected to the housing for closing the open end. The end plate has at least one inlet opening and an outlet opening therein. An anti-drain back valve is provided for precluding return flow of oil through the inlet opening. An annular filter media is disposed in said housing. An end cap is provided at each end of the filter media. The end cap remote from the end plate has at least one opening spaced radially outwardly from the central axis thereof. A spring cooperates with said end cap remote from the end plate. Normally, the opening in the spring is closed to oil flow. When the filter media becomes clogged, the pressure within the housing increases and when the pressure differential across the end cap remote from the end plate exceeds a predetermined value, the opening in the spring is opened for oil flow. The anti-drain back valve is disposed between the end cap adjacent the end plate and the end plate and the spring is constructed and arranged to engage the interior of the housing so as to load the filter media and the end cap adjacent to the end plate to help retain the anti-drain back valve in place. A seal is provided between the end cap remote from the end plate and the spring. The spring and the end plate remote from the end plate are constructed and arranged to operationally interengage and provide a relatively flat profile.

BACKGROUND OF THE INVENTION

[0001] The present invention pertains to fluid filters and, more particularly, an end cap relief valve mechanism for a fluid filter.

[0002] Ordinarily, fluid filters, such as oil filters, are provided with relief valves in order to bypass the filter element in the event that the oil filter becomes clogged during use. The oil filter usually comprises a housing or shell having an open end closed by an end plate. The end plate usually contains one or more inlet openings and an outlet opening. Within the housing is an annular filter media pack. Normally, there is a valve comprised of a valve seat, a valve member and a spring for biasing the valve to the closed position disposed within the housing. The valve is commonly secured to the filter media pack.

[0003] Takahara Patent No. 5,759,351 shows an oil filter having a plate spring for biasing a filter pack within a housing. When the filter pack becomes clogged, the pressure in the housing increases and the relief valve opens to keep the flow rate of the oil supplied to the engine. The filter pack does not include end caps and the relief valve of Takahara is structurally different from that of the applicant.

[0004] Sundholm Patent No. 5,019,251 discloses a filter having a relief valve mechanism with a spiral spring that is relatively bulky.

[0005] Cantoni Patent No. 4,885,082 reveals an oil filter with a multi-component pressure relief valve having a bulky return spring. The prior art relief valves, as exemplified by those shown in the cited references, are constructed separate from the end cap, and proper positioning of the valve within the housing of the fluid filter was sometimes difficult and/or time consuming. The prior relief valves were relatively bulky and occupied considerable volume within the housing of the oil filter. Consideration was given to reducing the number of parts of the valve in order to reduce the cost and to enhance positioning of the valve and facilitate assembly of the fluid filter.

[0006] An object of the present invention is to provide an improved fluid filter having a relief valve mechanism formed in part by an end cap, which overcomes difficulties and disadvantages of prior fluid filters.

[0007] Another object of the present invention is to provide an improved fluid filter that incorporates a relief valve mechanism as a part of an end cap to provide a relief valve mechanism that is compact, has a low profile and is less costly than prior relief valve mechanisms, thus allowing the fluid filter to be shorter, yet have the same filtration and flow characteristics as prior taller fluid filters.

[0008] Other objects and advantages of the present invention will be made more apparent in the description which follows.

SUMMARY OF THE INVENTION

[0009] A fluid filter, for example, an oil filter comprises a housing that is open at one end and closed at the other end by an end plate. The end plate has at least one inlet opening and one outlet opening therein. Filter media is disposed in the housing. An end cap is provided at each end of the filter media. An anti-drain back valve, disposed between the end plate and an end cap of the filter media adjacent the end plate, cooperates with the inlet opening to prevent the back flow of oil there through in use. The end cap remote from the end plate has at least one opening in the central portion thereof. A spring cooperates with the end cap remote from the end plate to close the opening in the end cap and is responsive to the pressure within the housing to open the flow path when the oil pressure in the housing exceeds a predetermined value. The end cap remote from the end plate and the spring comprise a relief valve mechanism. The spring also functions to load the filter media and to retain the anti-drain back valve in position between the end cap adjacent the end plate and the end plate. The spring is provided with spaced projections which maintain a flow path should the spring be flattened against the interior of the housing and thereby permit flow of oil around the spring to permit desired operation of the relief valve mechanism. The spring and the end cap remote from the end plate are constructed and arranged to provide an end cap relief valve mechanism that has a flat profile and occupies little more space than the end cap alone.

BRIEF DESCRIPTION OF THE INVENTION

[0010] There is shown in the attached drawing a presently preferred embodiment of the invention, wherein like numerals in the various views refer to like elements and wherein,

[0011]FIG. 1 is a schematic perspective view, partially broken away, of a fluid filter embodying the end cap relief valve mechanism of the present invention, with the end cap valve mechanism being shown in the closed position;

[0012]FIG. 2 is a schematic perspective view, partially broken away, similar to FIG. 1, of a fluid filter embodying the end cap relief valve mechanism of the present invention, with the end cap relief valve mechanism being shown in the open position;

[0013]FIG. 3 is a plan view of the end cap of the end cap relief valve mechanism;

[0014]FIG. 4 is a cross-section of the end cap taken along the line 4-4 of FIG. 3;

[0015]FIG. 5 is a plan view of the spring of the end cap relief valve mechanism;

[0016]FIG. 6 is a cross-section of the spring taken along the line 6-6 of FIG. 5;

[0017]FIG. 7 is a detail cross-section taken generally along the line 7-7 of FIG. 5;

[0018]FIG. 8 is a cross-section showing the relationship of the end cap and the spring of the end cap relief valve mechanism, with the end cap relief mechanism shown in the closed position; and

[0019]FIG. 9 is a cross-section showing the relationship of the end cap and the spring of the end cap relief valve mechanism, with the end cap relief valve mechanism in the open position.

DETAILED DESCRIPTION OF THE INVENTION

[0020] There is shown in FIGS. 1 and 2 a schematic representation of a fluid filter 10 embodying the relief valve mechanism 12 of the present invention. The fluid filter 10, which can be an oil filter, includes a housing or shell 14 having a closed end 16 and an open end 18. The open end 18 of the housing 14 is closed by an end plate 20 that is provided with one or more inlet openings 22 disposed radially outwardly from the center axis of the fluid filter 10 and an outlet opening 24 disposed generally centrally of the end plate 20. The portion of the end plate 20 forming the outlet opening 24 is internally threaded so as to receive an externally threaded engagement member (not shown). Other connections may be used, as would be known to persons skilled in the art. The end plate 20 is suitably positioned and secured in the open end 20 of the housing 14. A cover or end ring 21 is secured to the housing 14 outwardly from the end plate 18 in a conventional manner, for example, by a double-rolled seam. The cover 21 has a circular recess 23 formed therein for receiving a sealing gasket 26.

[0021] Disposed within the housing 14 is a filter media pack 30 which comprises a central perforated core 32 having a suitable filter media 34 carried thereon. The core 32 is typically fabricated from relatively thin sheet metal, such as steel or aluminum, that is stamped to provide the openings in the core and is then coiled to form a cylinder of the desired diameter. The filter media 34 may comprise a conventional pleated paper or a wound filter media. Each end of the filter media 34 may be potted in a suitable adhesive or plastisol to help maintain the shape of the filter media during handling and in use. See, for example, the adhesive 29 at the lower end of the filter media 34. For purposes of better showing the top of the pleated filter media, no adhesive is shown at the upper end of the filter media 34 in FIGS. 1 and 2.

[0022] An end cap 40 closes the lower end of the filter media pack 30. The end cap 40 may be secured to the filter media 34 or it can be separate therefrom. The end cap 40 comprises a support member 46, which engages the lower end of the filter media 34 and a generally cylindrical portion 48 having a circular flange 47 at the lower end that engages the portion of the end plate 20 that forms the outlet opening 24. The flange 47 cooperates with the end plate 20 to help retain a resilient valve member 49 in place. The valve member 49, which may be made from a natural or an artificial rubber, functions to permit the entry of fluid through the inlet openings 22 into the housing 14, but to prevent the reverse flow of oil through the openings 22. The valve member 49 is sometimes referred to as an anti-drain back valve.

[0023] The relief valve mechanism 12 of the present invention includes a generally circular end cap 50, which is remote from the end plate 20, and extends over the top of the filter media pack 30 and engages the upper end thereof. The end cap 50 may be secured to the filter media 34 or it can be separate therefrom. The end cap 50 is imperforate except for one or more openings 52 spaced radially outwardly from the center thereof. The openings 52 are arranged in a circular pattern that is spaced radially outwardly from the center axis of the end cap 50. The end cap 50 includes a cylindrical peripheral rim 54 that has an outwardly flared flange 56 at the lower end thereof. Cooperating with the end cap 50 is a valve spring or plate spring 60 that performs multiple functions. First, the spring 60 abuts the interior of the housing 14 and loads or pushes the filter media pack 30 downwardly toward the end plate 20 so as to urge the lower end cap 40 downwardly against the anti-drain back valve 49 to retain the anti-drain back valve 49 in place. Second, the spring 60 cooperates with the end cap 50 to normally close the flow path through the openings 52 and in response to a predetermined pressure within the housing 14 to open the flow path through the openings 52, as will be more fully explained hereinafter.

[0024] Turning to FIGS. 3 and 4 there is better seen the end cap 50 of the present invention. The end cap 50 has a relatively flat profile. The central portion 51, which is imperforate except for the openings 52, is depressed from the top outer surface of the end cap 50. The openings 52 are shown as being circular, however, it will be understood by person skilled in the art that other configurations are possible within the scope of the invention. The openings 52 could be square, oval, or crescent shaped. Furthermore, the size of the openings 52 could be varied depending upon the specific design parameters for flow necessary with a particular fluid filter. The top surface of the end cap 50 is provided with a ridge or elevated circular portion 53 that will help stiffen or rigidify the end cap 50 in use.

[0025] With reference to FIGS. 5-7, there is better shown the spring 60 that controls the flow of fluid through the openings 52 in the end cap 50 and helps to retain the anti-drain back valve 29 in position between the lower end cap 40 and the end plate 20. The spring 60, as shown, is comprised essentially of a plate made, for example, from steel, formed to shape. The spring 60 includes four outwardly extending arm portions 62 that extend upwardly from the central portion 68. The ends 64 of the arm portions 62 are bent downwardly. The central portion 68 of the spring 60 is relatively flat and has an opening 70 in the center thereof, which is in alignment with the imperforate central portion 51 of the end cap 50. Provided in the spring 60 are depressions 72 which are intended to assure that a spacing remains between the interior of the housing 14 and the spring 60 and to provide a flow path should the spring 60 be flattened against the interior of the housing. This construction assures that there will be flow of oil over the top of the valve spring 60 so as to enable proper operation of the relief valve mechanism.

[0026] With reference to FIGS. 8 and 9, there is better shown the cooperation of the spring 60 and end cap 50 of the end cap relief valve mechanism 12. The spring 60 and the end cap 50 operationally interengage and provide a relatively flat profile. The overall height of the two components when assembled within a housing or shell 14 is little more than the height of the end cap 50. Seal means are provided between the end cap 50 and the spring 60 to prevent fluid from passing directly to the openings 52 and bypassing the opening 70 in the spring 60. In the embodiment shown, the flattened annular portion 71 radially outward of the annular portion 69 extending from the central portion 68 of the spring 60 engages the flattened radial portion 73 radially outward of the annular portion 55 extending from the central portion 51 of the end cap 50 to provide a seal for preventing fluid from passing between the end cap 50 and the spring 60 and bypassing the opening 70 in the spring 60. In the closed position shown in FIG. 8, the central portion 51 of the end cap 50 is positioned upwardly so as to close the opening 70 in the spring 60 and thus block the flow of fluid (oil) through the end cap relief valve mechanism 12. This is the normal position of the central portion 51. When the pressure within the housing 14 increases and the fluid pressure differential on the central portion 51 of the end cap 50 exceeds a predetermined value, the central portion 51 of the end cap 50 below the opening 70 in the spring 60 will flex downwardly, as shown in FIG. 9, to open a flow path through the end cap relief valve mechanism 12.

[0027] The operation of the fluid filter 10 will now be described. With reference to FIG. 1, the fluid filter 10 is connected to an engine in the normal manner. With the engine operating, oil to be cleaned will enter the housing 14 of the fluid filter 10 through the opening or openings 22 in the end plate 20. Oil will pass through the filter media pack 30 to be cleaned and through the openings in the core 32 of the filter media pack 30 for return through the outlet opening 24 to the engine for reuse. If in use, the filter media pack 30 becomes clogged with dirt and impurities removed from the oil, the pressure within the housing 14 will increase. As shown in FIG. 2 and in FIG. 9, when the pressure differential across the end cap exceeds a predetermined value, the central portion 51 of the end cap 50 will flex and separate from the spring 60 and permit oil to flow through the opening 70 in the spring 60 and the openings 52 in the end cap 50 and be returned to the engine. The bypass or return of oil to the engine in the event of a clogged or substantially clogged filter media pack 30 will prevent damage to the engine.

[0028] The end cap relief valve mechanism of the present invention comprises basically two elements-an end cap and a spring that cooperates therewith. Since there are only two parts, parts costs and manufacturing costs are reduced. Parts costs are also reduced by making use of the end cap that is normally used with one end of a filter media pack. It will be understood that the end caps can be integral with filter media or they can be separate from the filter media. Further, it will be understood that the end cap may comprise only the central portion 51 that cooperates with a spring 60 to perform the flow control function. In the preferred embodiment, the profile of the end cap relief valve mechanism 12 is relatively flat and occupies little space beyond that of the end cap. This allows the fluid filter of the present invention to be shorter than prior devices, yet have the same filtration and flow characteristics as such prior taller fluid filters. The spring 60 not only provides a portion of the relief valve but also a loading function to bias the filter media pack 34 and the end cap 40 toward the end plate 20 to retain the anti-drain back valve 29 in place between the end cap 40 and the end plate 20. It is possible to use a different spring, for example, a coil spring, however, some attributes of the preferred embodiment may be sacrificed.

[0029] While we have shown a presently preferred embodiment to the present invention, it will be apparent to persons of ordinary skill in the art that the invention may be otherwise embodied within the scope of the appended claims. 

We claim:
 1. In a fluid filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an annular filter media disposed in said housing, said filter media having an end cap at each end, and a valve member for controlling flow of fluid through the inlet opening, the improvement comprising the end cap remote from the end plate having at least one opening in the central portion thereof and a spring cooperating with said end cap remote from the end plate and closing said opening to fluid flow, the end cap being responsive to the pressure within the housing for opening the said opening when the fluid differential pressure across the end cap exceeds a predetermined value.
 2. A fluid filter as in claim 1, wherein the end cap remote from the end plate has a plurality of openings in the central portion spaced radially outwardly from the central axis of the end cap and the spring controls the flow of fluid through said openings.
 3. A fluid filter as in claim 1, wherein the valve member comprises an anti-drain back valve disposed between the end cap adjacent the end plate and the end plate, said spring being constructed and arranged to engage the interior of the housing so as to load the filter media and the end cap adjacent to the end plate to help retain the anti-drain back valve in place.
 4. A fluid filter as in claim 3, wherein the spring includes outwardly extending arms extending upwardly from the central portion of the spring valve.
 5. A fluid filter as in claim 4, including depressions on the spring between the arms for providing a flow path should the spring be flattened against the interior of the housing in use.
 6. A fluid filter as in claim 2, wherein the central portion of the end cap remote from the end plate is capable of being flexed from a first position against the spring to a second position away from the spring.
 7. A fluid filter as in claim 6, wherein the spring valve has a central opening therein, the central portion of the end cap remote from the end plate closing the central opening when in the first position and opening the central opening when flexed to the second position, whereby, the spring is normally in the first position closing flow of fluid and when the pressure within the housing increases and the differential pressure across the end cap exceeds a predetermined value, the central portion of the end cap remote from the end plate is flexed to the second position to permit flow of fluid.
 8. An oil filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an anti-drain back valve for precluding return flow of oil through the inlet opening, an annular filter media disposed in said housing, said filter media having an end cap at each end, the end cap remote from the end plate having at least one opening spaced radially outwardly from the central axis thereof and a spring valve cooperating with said end cap remote from the end plate for closing said opening to fluid flow, whereby when the pressure within the housing increases and the pressure differential across the end cap exceeds a predetermined value, the said opening will be opened to permit fluid flow therethrough.
 9. An oil filter as in claim 8, wherein the end cap remote from the end plate has a plurality of openings in the central portion spaced radially outwardly from the central axis of the end cap and the spring cooperates with the end cap to control the flow of fluid through said openings.
 10. An oil filter as in claim 9, wherein the anti-drain back valve is disposed between the end cap adjacent the end plate and the end plate, said spring being constructed and arranged to engage the interior of the housing so as to load the filter media and the end cap adjacent to the end plate to help retain the anti-drain back valve in place.
 11. An oil filter as in claim 10, wherein the spring includes outwardly extending arms extending upwardly from the central portion of the spring.
 12. An oil filter as in claim 11, including depressions on the spring between the arms for permitting fluid flow between the spring valve and the interior of the housing and providing a fluid flow path should the spring be flattened against the interior of the housing in use.
 13. An oil filter as in claim 9, wherein the central portion of the end cap remote from the end plate is capable of being flexed from a first position against the spring to a second position away from the spring.
 14. An oil filter as in claim 13, wherein the spring has a central opening therein, the central portion of the end cap remote from the end plate closing the central opening when the first position and opening the central opening when flexed to the second position, whereby, the spring is normally in the first position closing flow of oil and oil entering the housing through the inlet opening in the end plate passes through the filter media to be cleaned and when the filter media becomes clogged, the pressure within the housing increases and when the pressure differential across the end cap exceeds a predetermined value, the central portion of the end cap remote from the end plate is flexed to the second position to permit oil to bypass the filter media and flow from the inlet opening in the end plate, through the central opening in the spring and the openings in the end cap remote from the end plate and out the outlet opening.
 15. An oil filter as in claim 13, wherein the spring and the end plate remote from the end plate are constructed and arranged to operationally interengage and provide a relatively flat profile.
 16. An oil filter as in claim 8, including seal means between the end cap remote from the end plate and the spring to prevent oil from passing directly to the opening in the end cap remote from the end plate and bypassing the opening in the spring valve.
 17. An oil filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an anti-drain back valve for precluding return flow of oil through the inlet opening, an annular filter media disposed in said housing, said filter media having a first member at one end and an end cap at the other end, the first member having at least one opening spaced radially outwardly from the central axis thereof and valve means cooperating with said first member for closing said opening to fluid flow, whereby when the pressure within the housing increases and the pressure differential across the first member exceeds a predetermined value, the said at least one opening will be opened to permit fluid flow therethrough.
 18. An oil filter as in claim 17, wherein the first member and the valve means are sealingly engaged to one another radially outwardly of the opening in the first member.
 19. An oil filter as in claim 17, including seal means between the first member and the valve means to prevent oil from passing directly to the opening in the first member and bypassing the opening in the valve means. 